A New Sesquiterpene and Known Alkaloids from Toddalia asiatica and Their Inhibitions Against Phosphodiesterase-4

A new sesquiterpene (1) and nine known alkaloids (2-10) were isolated from the roots of Toddalia asiatica. The structure of compound 1 were resolved by NMR and HRESI data, as well as ECD calculation for determining the absolute configuration. The known compounds were identified to be 8-acetonyldihydronitidine (2), 8-acetonyldihydroavicine (3), dihydronitidine (4), oxynitidine (5), decarine (6), skimmianine (7), g-fagarine (8), N-methylflindersine (9), and 4-methoxy-N-methyl-2-quinolone (10) by comparing the NMR data with those in the literature. Compound 1 is the first eremophilane-type sesquiterpenoid isolated from this species. The known compounds 2, 3, and 6 were discovered for the first time from the genus Toddalia. All the isolated compounds were evaluated for their inhibitory effects against phosphodiesterase-4, as result, compound 2 showed strong inhibitory effect against phosphodiesterase-4 with an IC50 value of 5.14 mM.